/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.pig.newplan.logical.visitor;
import org.apache.pig.PigException;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.plan.VisitorException;
import org.apache.pig.newplan.DependencyOrderWalker;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.PlanWalker;
import org.apache.pig.newplan.ReverseDependencyOrderWalker;
import org.apache.pig.newplan.logical.expression.LogicalExpressionPlan;
import org.apache.pig.newplan.logical.expression.LogicalExpressionVisitor;
import org.apache.pig.newplan.logical.expression.ProjectExpression;
import org.apache.pig.newplan.logical.relational.LOFilter;
import org.apache.pig.newplan.logical.relational.LOLimit;
import org.apache.pig.newplan.logical.relational.LogicalRelationalNodesVisitor;
/**
* This validator checks the correctness of use of scalar variables in logical
* operators. It assesses the validity of the expression by making sure there is
* no projection in it. Currently it works for Limit and Sample (see PIG-1926)
*
*/
public class ScalarVariableValidator extends LogicalRelationalNodesVisitor {
public static final String ERR_MSG_SCALAR = "Expression in Limit/Sample should be scalar";
public ScalarVariableValidator(OperatorPlan plan) throws FrontendException {
super(plan, new DependencyOrderWalker(plan));
}
@Override
public void visit(LOLimit limit) throws FrontendException {
LogicalExpressionPlan expression = limit.getLimitPlan();
if (expression != null) {
ProjectFinder pf = new ProjectFinder(expression,
new ReverseDependencyOrderWalker(expression));
pf.visit();
if (pf.found()) {
int errCode = 1131;
throw new VisitorException(limit, ERR_MSG_SCALAR, errCode,
PigException.INPUT);
}
}
}
@Override
public void visit(LOFilter filter) throws FrontendException {
LogicalExpressionPlan expression = filter.getFilterPlan();
if (expression != null) {
// if it is a Sample, the expression must be scalar
if (filter.isSample()) {
ProjectFinder pf = new ProjectFinder(expression,
new ReverseDependencyOrderWalker(expression));
pf.visit();
if (pf.found()) {
int errCode = 1131;
throw new VisitorException(filter, ERR_MSG_SCALAR, errCode,
PigException.INPUT);
}
}
}
}
public static class ProjectFinder extends LogicalExpressionVisitor {
private boolean foundProject;
public boolean found() {
return foundProject;
}
protected ProjectFinder(OperatorPlan p, PlanWalker walker)
throws FrontendException {
super(p, walker);
}
@Override
public void visit(ProjectExpression project) {
foundProject = true;
}
}
}